Since the designation was established in 1978, 19 NHTs have been designated, ranging in length from the 54-mile Selma to Montgomery National Historic Trail to the 5,665-mile California National Historic Trail. To qualify as NHTs, trails must meet three criteria under the National Trails System Act (NTSA). They must be travel routes that (1) were originally established by historic use; (2) have been determined to be of national significance because of that use; and (3) have significant potential for public recreational use or historic interest. Congress designates NHTs through amendments to the NTSA.

In addition to recognition, becoming an NHT provides trails with permanent federal designation as part of an established program. The designation authorizes the trail administration to “enter into cooperative agreements with States and political subdivisions, landowners, organizations, and individuals to operate, develop and maintain any portion of the trail.” It also allows partners to obtain technical and financial assistance from the National Park Service (NPS)—subject to the availability of funding—for preservation, interpretation, signage, promotion, research, and other efforts related to eligible historic resources.